Method of dyeing fibers

ABSTRACT

A method of dyeing a textile fiber selected from the group consisting of the modified polyester, polyvinyl chloride, polyacrylonitrile and cellulose acetate fibers, such method comprising dyeing the fibers with an anionic dyestuff in the presence of at least one compound selected from tertiary tributyl phosphine and triphenyl phosphine.

United States Patent 1191 Shimauchi et a1.

METHOD OF DYEING FIBERS Inventors: Shiro Shimauchi; Norihiro Minemura; Takeshi Matsui; Kenji Ito Osaka; Taken Shima; Shoji Kawase; Masataka Oshima, all of lwakuni, Japan Teiiin Limited, Kita-ku, Osaka, Japan Filed: Feb. 29, 1972 Appl. No.: 230,497

Related US. Application Data Division of Ser. No. 804,294, March 4, 1969, Pat. No. 3,666,403.

Assignee:

us. (:1. 8/171, 8/168 1111. c1 006 5/04 116111 61 Search 8/168, 172, 85, 84,

References Cited UNITED STATES PATENTS 6/1961 Mautner 8/172 X OTHER PUBLICATIONS Exparte Schoover et al., decision of the Board of Appeals, Pat. No. 2,743,991 Paper No. 23, 6 pp.

Exparte Schoeneberg et a]., decision of the Board of Appeals Pat. No. 3,190,718, Paper No. 27, four pages.

Primary Examiner-Mayer Weinblatt Assistant Examiner-T. .1. Herbert, Jr. Attorney-Leonard W. Sherman et a1.

[5 7] ABSTRACT A method of dyeing a textile fiber selected from the group consisting of the modified polyester, polyvinyl chloride, polyacrylonitrile and cellulose acetate fibers, such method comprising dyeing the fibers with an anionic dyestuff in the presence of at least one compound selected from tertiary tributyl phosphine and triphenyl phosphine.

3 Claims, No Drawings 1 METHOD OF DYEING FIBERS This application is a division of application Ser. No. 804,294, filed March 4, 1969 now US. Pat. No. 3,666,403 issued May 30, 1972.

This invention relates to a method of dyeing modified polyester, polyvinyl chloride, polyacrylonitrile or cellulose acetate fibers with an anionic dyestuff. More particularly, this invention relates to a method of dyeing a fiber selected from the group consisting of the modified polyester, polyvinyl chloride, polyacrylonitrile and cellulose acetate fibers with an anionic dyestuff in the presence of at least one compound selected from tributyl phosphine and triphenyl phosphine.

Fibers manufactured from such synthetic polyesters as polyethylene terephthalate do not have any affinity at all for the ionic dyestuffs and accordingly they were previously dyed principally by means of disperse dyes. However, disperse dyes are costly and moreover the dyed products obtained by their use were not satisfactory with respect to brightness. Therefore, there was a strong demand in the trade for the modification of the polyester fibers so that they could be dyed by means of ionic dyestuffs, particularly acid dyes. it is therefore a primary object of this invention to provide a method by which modified polyesters can be dyed to deep shades.

Numerous methods of dyeing polyvinyl chloride fibers are known. For instance, there is a dyeing method which comprises preparing and insoluble complex with an acid dye and a cationic surfactant and using this complex for dyeing the fibers; however none of the conventional methods have been able to provide dyed products which are fully deep in shade. Therefore, a second object of the invention is to provide a dyeing method by which polyvinyl chloride fibers can be dyed to fully satisfactory deep shades.

Only acrylonitrile fibers are usually dyed with cationic dyestuffs. However, in this case also, when expansion of the scope of color and when the case of dyeing of mixed spun products are considered, the impartation of dyeability by means of the acid dyes is desirable. A third object of the present invention is therefore to provide a dyeing method which expands the scope of color of the dyed products of polyacrylonitrile fibers as well as facilitates the dyeing of mixed spun products, especially mixed spun products with wool.

Cellulose acetate fibers are also dyed with disperse dyes as in the case with polyester fibers, but in this case also the shortcoming was noted that the brightness of the dyed product was not yet fully satisfactory. A fourth object is therefore to provide a dyeing method which can impart excellent dyeability to cellulose acetate fibers and dye these fibers to bright shades.

Other objects and advantages of this invention will become apparent from the following description.

Research was conducted both from the aspect of the modification of the polyester fiber and the method of dyeing the same. As a consequence it was found that shaped articles of certain classes of modified polyesters could be dyed to exceedingly deep shades when dyed by an anionic dyestuff in the presence of at least one compound selected from tributyl phosphine and triphenyl phosphine.

Polyesters, as used herein, are principally intended to be polyethylene terephthalate. However, the expres sion polyester", also refers to those polyesters which comprise at least 60 mol percent of ethylene ten:-

phthalate units and in which part of the acid or dihydroxy component is substituted by one or more classes of either difunctional or hydroxy acids such as isophthalic acid, compounds having metal salts of sulfonic acid, beta-hydroxyethoxy-benzoic acid, p hydroxybenzoic acid, diphenyldicarboxylic acid, naphthalenedicarboxylic acid, diphenylsulfonedicarboxylic acid, adipic acid and sebacic acid, or the aliphatic, alicyclic and aromatic dihydroxy compounds such as diethylene glycol, trimethylene glycol, hexamethylene glycol, neopentylene glycol, 1,4- cyclohexanedimethanol, 2,2,4,4,-tetramethylcyclobutanediol-( 1,3), l,4-bishydroxyethoxybenzene, bisphenol A and compounds having the tertiary amino group (e.g. butyldi-(betahydroxyethyl) amine). Further, polyesters in which a minor proportion of a mono fuctional compound such as benzoylbenzoic acid and /or a polyfuctional compound such as pentaerythroitol and trimesic acid are copolymerized to a certain extent with substantial cross-linking are applicable. In the preparation of these polyesters, th the known catalysts and additives such as stabilizers, delustrants, etc., can be added with no trouble at all.

The term modified polyester compositions, are used herein, refers to the blend composition of a polyamide and a polyester obtained as hereinbefore described, the blended composition of a polyamide and a copolyester obtained by copolymerizing a polyalkylene glycol with a polyester, the blended composition of a polyester and a polyamide blend containing a polyalkylene glycol, and the blended composition of a polyester, polyamide and polyalltylene glycol. Modified polyester fibers which are particularly desirable include: (a) those obtained by melt-spinning ablended composition of 60 99.5 wt. of a polyester and 40 0.5 wt. of a polyamide and drawing the resulting filaments; (b) these obtained by melt-spinning a blended composition of 40 0.5 wt. of a polyamide with 60 99.5 wt. of a copolyester obtained by copolymerizing with a polyester 1 30 wt. based on the overall weightof the composition, of a polyalkylene glycol and drawing the resulting filaments; (c) those obtained by meltspinning a blended composition of 99.5 60 wt. of a polyester and 0.5 40 wt. of a polyamide blend containing, based on the overallweight of the composition, 1 30 wt. of a polyalkylene glycol, and drawing the resulting filaments; .(d) those obtained by meltspinning a blended composition consisting of60 99.5 wt. of a polyester, 0.5 40 wt of a polyamide and 0.6 30 wt. of a polyalkylene glycol and drawing the resulting filaments; (e) those obtained by melt-spinning a blended composition of 60 99.5 wt. of a polyester and 40 0.5 wt. of a polyamide and drawing the resulting filaments, then shrinkinggthefilaments by heat treating them and thereafter redrawing the filaments;

(f) those obtained by melt-spinning a blended composition of 60 99.5 wt. of a polyester and 40 0.5 wt. of a polyamide, and drawing the resulting filaments then shrinkingthe filaments 2 to SO percent at a temperature ranging between C. and the melting temperature of the polyester fiberandthereafter redrawing the filaments; and (g) those obtained by melt-spinning a blended composition of 60 99.5 wt. of a polyester and 40 0.5 wt. of a polyamide and drawing the re sulting filaments, followed by shrinking the filaments by heat treating them and thereafter redrawing the filaments at a temperature ranging between room temperature and 230C. and a draw ratio ranging from 2 percent to the point at which breakage of the polyester fiber takes place.

The manufacture of a fiber by melt-spinning and drawing a blended composition of a polyester and some amount of polyamide is known (British Patent Specification No. 6l0,l40). However, the fiber which has been merely melt-spun and drawn in this manner does not demonstrate desirable dyeability when the usual method of dyeing it with anionic dyestuffs is employed. It is only when the fiber is dyed by the dyeing method of the present invention that it is possible to provide products dyed to bright and deep shades so as to be very useful.

As a result of further research with a view to improving the dyeability of the fiber itself obtained from the polyester-polyamide composition it was found that when one of the methods of the present invention, i.e., that wherein the fiber formed by melt-spinning and drawing the aforementioned polyester composition is then shrunk 2 50 percent at a temperature ranging between 140C. and the melting temperature of the polyester fiber, and thereafter it is again drawn at a temperature between room temperature and 230C. and a draw ratio ranging between 2 percent and the point at which its breakage takes place is employed and the so obtained fiber is used in combination with and anionic dye and at least one compound selected for tributyl phosphine and triphenyl phosphine, dyed products which are of greater brightness and of deeper shades can be obtained. Accordingly, the hereinabove indicated heat treatment and redrawing conditions are both important. Thus, fibers having excellent dyeability cannot be obtained in those cases where either one of these conditions are lacking.

Further, ultraviolet absorbents can be used in the dyeing method of the present invention for improving the light fastness of the dyed product. The following compounds can be used as ultraviolet absorbents in the present invention. 1. 2-(2-hydroxyphenyl) benzotriazole series, for example, those such as follows:

2. 2-hydroxybenzophenone serie, for example, those of the following formulas:

wherein R is H, -C,,H (wherein n is 1-18),

(where R is alkyl or aryl); and

OH O wherein R is H or -SO;,H. 3. 2,2 -dihydroxybenzophenone series, for example, those of the formula wherein R is H, C,,H (where n 1-18),

(where R is alkyl or aryl).

4. Phenylsalicylic acid series, for example, those of the formula wherein R is H, C,,H (wherein n ll8),

JLR

(where R' is alkyl or aryl).

5. Substituted acrylonitrile series, for example, those of the formulas ii-o-at wherein R is alkyl or aryl.

While the amount of these ultraviolet absorbents used will vary depending upon the class of the material to be dyed, the class of the dyestuff and the concentration and bath ratio, etc., the use of about 1 10 percent (o.w.f.) based on the material to be dyed will do. It is also possible to achieve the result desired by imparting the ultraviolet absorbent to the fiber using a separate bath.

Again, the modified polyester composition of the present invention not only possesses excellent affinity for anionic dyestuffs, as noted hereinbefore, but also demonstrates satisfactory affinity for disperse dyes. In addition, it can also be dyed satisfactorily by means of the basic dyes in the presence of anionic substances. As anionic substances, included are inorganic acids such as sulfuric and acetic acids and the salts thereof; and benzenesulfonic acid, toluenesulfonic acid, higher alkylbenzenesulfonic acids, and sulfuric esters of higher alcohols and the salts thereof; and phenols.

There are no particular restrictions as to the polyamides to be used in the present invention as long as they are serviceable with respect to their thermal resistance, etc. Mention can be made of such, for example, as polycaproamide, polyenanthamide, polyundecamide, polyhexamethylene adipamide and polymetaxylene adipamide, or copolymers of these with other amideforming substances. These polyamides can be used ei- [her alone or in combinations of two or more thereof. Of these polyamides, the aromatic polyamides such, for example, as those which have copolymerized therewith the hexamethylene-diammonium terephthalate component give especially desirable results with respect to compatibility. These polyamides are incorporated in the polyester in an amount of 0.5 50 percent by weight, and preferably 5 to percent by weight. If the content of polyamide is less than 0.5 percent by weight, the affinity of the resulting fiber for ionic dyestuffs is inadequate. On the other hand, if the content of the polyamide exceeds percent by weight, the properties as a polyester fiber are lost. Accordingly it is undesirable for the content of the polyamide to be outside the range indicated above.

In addition, the dyeability of the fiber can be further enhanced by incorporating in the foregoing polyesters and/or polyamides in an amount not exceeding 30 percent by weight, based on the overall weight of the fiber, at polyoxyalkylene glycol. As the polyoxyalkylene glycol, mention can be made of such, for example, as polyoxyethylene glycol, polyoxypropylene glycol, polyoxyethylene-oxypropylene glycol block or random copolymer, methoxypolyoxyethylene glycol, phenoxypolyoxyethylene glycol and octylphenoxypolyoxyethylene glycol. These polyoxyalkylene glycols may be present in either the polyester or the polyamide, or in both components. It may be added either during the early stages of the manufacture of the polyester or during the blending of the components.

It does not matter whether the polyvinyl chloride fiber used in the present invention is a homopolymer, a copolymer or an after-chlorinated product.

Good results can naturally be expected even if this method is applied to the mixed woven products of polyvinyl chloride fiber and other classes of fibers. Moreover, in the case of a mixed spun product of polyvinyl chloride fiber with wool, there is a great advantage in that the two fibers can be dyed with the same acid dye in a single bath.

As the polyacrylonitrile fibers to be used in the pres ent invention acrylic fibers that do not possess dye receptive sites are useable. Included are the Orlon (trademark of DuPont Company) type, and the acrylic conjugated fiber. Again, it goes without saying that the present invention also has applicability to the mixed textile products of the foregoing fibers with other classes of fibers.

As the cellulose acetate fibers to be used in the present invention, included are the usual diacetate to triacetate fibers. Again, the present invention can also be applied to the cellulose acetate fibers obtained by the after acetylation technique. Again, the invention can, of course, be applied to the mixed textile products of the foregoing fibers with other classes of fibers. The method of the present method is especially effective in the case of a mixed product of acetate fibers with polyamide fibers, since both fibers aredyeable with acid dyes.

The modified polyester fibers that can be dyed by means of the method of the present invention are the so-called readily dyeable polyester fibers whose dyeability by means of disperse dyes has been improved, as hereinafter described, by either an elevated temperature treatment or the introduction (blending or copoly merizing) of a third component. The term readily dyeable polyester fibers, as used herein, denotes those fibers having a dye adsorption of at least 60 percent as determined by the method of measurement of the rate of dye adsorption as defined below.

The rate of dye adsorption is determined in the following manner. The specimen is washed in a l00-fold amount of distilled water (C.) for 30 minutes with stirring, followed by air drying and thorough opening of the fiber. One gram of the so standardized specimen is weighed and dyed under the following conditions:

After completion of the dyeing and cooling to room temperature, a suitable amount of the remaining dye liquor is taken and combined with an equal amount of C.P. acetone (reagent), following which this acetonewater (1:1) mixture isdiluted 25 times and the optical density is measured a spectrophotometer. Next, the before-dyeing dye liquor diluted in a similar man ner is measured for its optical density. The rate of dye adsorption is then obtained by the following equation, the average of three measurements rounded to whole numbers being used.

Dye adsorption (l d/d,,) X I00 wherein d, the optical density of the before-dyeing dye liquor and d the optical density of the after-dyeing remaining liquor.

Polyester fibers having a dye adsorption of below 60 percent cannot provide satisfactory dyed products even though the method of the present invention is used.

If the present invention is applied to polyamide fibers (e.g. nylon) the results are negative. This is believed to be due to the fact that the dye is not dissociated as a result of the anionic dye forming a complex, with the con sequence that in the case of the polyamide fibers having dye receptive sites the results are negative as a result in the decline in the dye absorption.

Further, the anionic dyestuffs, as referred to herein, denote all of the those dyes having an anionic group, i.e., the acid dyes, direct dyes, metal complex dyes, reactive dyes and acid mordant dyes.

In practicing the present invention, the dyeing methods that can be used include the various conventional methods such as the dip, padding and printing techniques.

The dyeing conditions will vary depending upon the class and form of the textile to be dyed and the class of dyeing method to be employed. For instance, in the case of the most widely practiced dip method, the dye ing conditions will be as indicated: below.

In the case of the method of dyeing the modified polyester fiber, the aforementioned compounds are added to the dye bath in a concentration of 1 100 percent o.w.f. A dyeing temperature of below 100C. does not result in a satisfactory dye adsorption, therefore a temperature exceeding 100C. is required. Usually, the dyeing is carried out at a temperature of 1 10 130C. until the intended color deepness is obtained. Again, carrier dyeing can also be carried out effectively using known carriers conjointly. In addition, it is also possible to make conjoint use of the organic and inorganic acids or salts in carrying out the dyeing operation.

On the other hand, in the case of the method of dip dyeing polyvinyl chloride fibers, the dyeing may be carried out at 50 100C. using the aforesaid compounds in a concentration of about 1 50 percent o.w.f. (percentage based on the weight of the material to be dyed), though varying depending upon the dyestuff used. Again, carrier dyeing can also be carried out effectively using known carriers conjointly.

Further, in the case of the cellulose acetate and polyacrylonitrile fibers, the amount of the compounds used will differ depending upon the concentration of the dyestufi' used, but usually the amount ranges from 1 to 100 percent. A dyeing temperature in the range of 80 120C. is convenient and, if possible, the higher, the better. Again, carrier dyeing is also effectively carried out by conjointly using known carriers.

As such known carriers, mention can be made of the phenolic compounds such as oand p-phenylphenol, the chlorobenzene type compounds such as monochlorobenzene, o-dichlorobenzene and trichlorobenzene,'

benzoic acid and benzoic acid type compounds such as benzoic acid, and the naphthalenic compounds such as methyl naphthalene. These carriers are added, for example, to the dye bath as an aqueous solution in the case of those which are water-soluble and as either a dispersion of emulsion in the case of those which are water-insoluble.

For carrying out level dyeing by dispersing the dyestuff thoroughly and for preventing the formation of tar, it is preferred to use a suitable monionic surfactant in the method of the present invention. Surfactants such as indicated are those which are usually widely used as dispersants. Included are, for example, the polyethylene glycol type surfactants such as polyethylene glycol alkylamines, polyethylene glycol alkyl ethers and polyethylene glycol aliphatic acid esters, and the ether or ester type surfactants which contain the polyhydric alcohols such as sorbitan aliphatic acid esters and aliphatic acid monoglycerides as the hydrophilic groups.

The textile which has been dyed in accordance with the method of the present invention is thoroughly soaped after its dyeing and thereafter submitted to reduction clearing, if necessary. The textile dyed by such method still retains adequate fastness even after it has undergone these after treatments.

Also better dye adsorption is obtained when the pH of the dye bath is on the acid side.

Next, examples will be given for further illustration of the present invention in detail. 1n the examples 'nsp/c indicates the specific viscosity measured at 35C. using orthochlorophenol as the solvent and intrinsic viscosity is defined as cc of solution. Also all parts are on a weight basis.

EXAMPLE 1 A autoclave was charged with 291 parts of dimethyl terephthalate, 207 parts of ethylene glycol, 29.1 parts of polyoxyethylene glycol (molecular weight about 1500), 0.102 part of calcium acetate monohydrate and 0.75 part of antimony trioxide. The autoclave was then gradually heated while slowly introducing nitrogen thereto, and the temperature was raised to 230C. over a period of about 3 7% hours while distilling off the methanol formed as a result of the ester-interchange reaction.

After completion of the distillation off of the methanol, 0.051 part of phosphoric acid was added, following which the temperature was raised to 275C. After stirring the reaction mixture at this temperature for 30 minutes under atmospheric pressure, the pressure of the reaction system was gradually reduced below 0.4 mmHg over a period of about one hour and 10 minutes.

The polyester which was obtained had an intrinsic viscosity of 0.65 and a softening point of 252.3C.

Fifty parts of the foegoing polyester and 10 parts of a polycaproamide having an intrinsic viscosity of 0.64 and a softening point of 2l3.7C., both of which were rendered into particle size having maximum diameters 3 5 mm, were mixed and then charged to an autoclave which, after having been purged with nitrogen, was reduced to a pressure below 2 mmHg.

This was followed by raising the temperature of the autoclave to 275C. where it was held for 30 minutes to effect the thorough melting of the two polymers, after which stirring was carried out for 30 minutes to obtain a blend having a softening point of 249.9C. After vacuum drying this polymer at C. for 4 hours, it was spun at 275C. and a spinning speed of 700 meters per minute, after which the freshly spun filaments were drawn 4.3 X to yield a fiber of 3.2 denier and having a tensile strength of 4.2 g/den and an elongation at break of 38 percent. The fibers obtained were dipped in a dye bath of the following composition:

Xylene Fast Blue PR (or. acid blue 129) 4% Triphenylphosphine 10% (o.w.f.) Acetic acid 4% (o.w.f.) (pH 3) Unlvadme W 4% (o.w.f.) Bath ratio 1:50

The fibers were dyed at C. for 9 minutes and thereafter soaped at 80C. for 30mi nutes in a 0.2 percent solution of Marseilles soap, with the result that a product dyed to a blue shade was obtained.

Although the so obtained dye product was exposed for 80 hours in a Fade-O-meter, no fading at all was observed.

EXAMPLE 2 a. Preparation of a blend of a polyamidc and a polyoxyalkylene glycol 250 Parts of hexamethylenediammonium adipate and 56 parts of methoxypolyoxyethylene glycol (average molecular weight about 4000) were dissolved in 300 --OCH:

The temperature of the residuum was then raised to 280C, at which temperature stirring was carried out for 60 minutes, after which the pressure of the system was gradually reduced to 0.7 mml-lg, at which the polymerization reaction was carried out for 20 minutes. The polyamide-polyoxyalkylene glycol blend obtained had an nsp/c of 1.13.

b. Preparation of the polyester composition Thirty-five parts of the foregoing blend and 165 parts of the polyester obtained in Example 2 were blended and spun, after which the resulting filaments were drawn, as described therein. The fibers obtained were dipped in a dye bath of the following composition:

Suminol Fast Red B 3% (o.w.f.) (C.l. acid red 6) Tributylphosphine (o.w.f.) UnivadineW 3% (o.w.f.) Acetic acid 5% (o.w.f.) Bath ratio 1:50

After the dyeing was carried out at 120C. for 60 minutes, soaping of the fibers was carried out at 80C. for 30 minutes in a 0.2 percent bright shade of red was obtained.

EXAMPLE 3 Twenty parts of a copolyamide (nsp/c 0.54) composed of 70 mol of caprolactam and 30 mol of hexamethylenediammonium terephthalate and 80 parts of polyethylene terephthalate were spun in customary manner at 285C. under nitrogen. The freshly spun filaments were drawn 4.3 X by means of an 85C. pin, then then shrunk 25 percent at a temperature of 230C. and thereafter again drawn 10 percent at a temperature of 150C.

The fibers obtained was dipped in a dye bath of the following composition:

Eriosin Red 2 EX 4 (o.w.f.) (C.l. Acid Red 116) Tributylphosphine l0 (o.w.f.) Bath adjusted to pH 2 with sulfuric acid Bath ratio 1:50

After carrying out the dyeing at 120C. for 90 minutes, soaping was carried out as in Example 1, whereupon a product dyed to a bright shade of red was obtained. Although this dyed product was exposed in a Fade-O-meter for 40 hours, no fading was observed.

We claim:

1. A method of dyeing a textile fiber selected from the group consisting of readily dyeable modified polyester fibers having a dye absorption of at least 60 percent, polyvinyl chloride fibers, polyacrylonitrile fibers and cellulose acetate fibers, such method comprising dyeing the fibers with an anionic dyestuff in the presence of at least one compound selected from tertiary tributyl phosphine and triphenyl phosphine.

2. The method of claim 1 wherein said modified polyester fibers are selected from the group consisting of:

a. that obtained by melt-spinning a blended composition of 60 99.5 percent by weight of polyester and 40 0.5 percent by weight of polyamide and draw ing the resulting filaments; (b) that obtained by melt-spinning a blended composition of 40 0.5 percent by weight of polyamide with 60 99.5 percent by weight of a copolyester obtained by copolymerizing with a polyester 1 30 percent by weight, based on the overall weight of the composition, of a polyoxyalkylene glycol, and drawing the resulting filaments; (c) that obtained by meltspinning a blended composition of 99.5 60 percent by weight of polyester and 0.5 40 percent by weight of a polyamide blend containing, based on the overall weight of the composition, l 30 percent by weight of a polyoxyalkylene glycol, and drawing the resulting filaments; (d) that obtained by melt-spinning a blended composition of 60 99.5 percent by weight of polyester, 0.5 40 percent by weight of polyamide and 0.6 30 percent by weight of polyoxyalkylene glycol and drawing the resulting filaments; (e) that obtained by melt-spinning a blended composition of 60 99.5 percent by weight of polyester and 40 0.5 percent by weight of polyamide, drawing the resulting filaments, followed by heat treating and shrinking the filaments, and thereafter again drawing the filaments; (f) that obtained by melt-spinning a blended composition of 60 99.5 percent by weight of polyester and 40 0.5 percent by weight of polyamide, drawing the resulting filaments, followed by shrinking the filaments 2 to 50 percent of their initial length by heating the filaments at a temperature within the range of C. and the melting temperature of said polyester filaments and thereafter again drawing the filaments, and (g) that obtained by melt-spinning a blended composition of 60 99.5 percent by weight of polyester and 40 0.5 percent by weight of polyamide, drawing the resulting filaments, followed by heat treating and shrinking the filaments, and thereafter again drawing said filaments at a rate of elongation ranging from 2 percent of their initial length to the point at which breakage of said polyester filaments takes place, at a temperature within the range of room temperature and 230C.

3. A method of dyeing a modified polyester textile fiber which comprises dyeing said fiber with an anionic dyestuff in the presence of tributyl phosphine or triphenyl phosphine. 

2. The method of claim 1 wherein said modified polyester fibers are selected from the group consisting of: a. that obtained by melt-spinning a blended composition of 60 -99.5 percent by weight of polyester and 40 - 0.5 percent by weight of polyamide and drawing the resulting filaments; (b) that obtained by melt-spinning a blended composition of 40 -0.5 percent by weight of polyamide with 60 - 99.5 percent by weight of a copolyester obtained by copolymerizing with a polyester 1 - 30 percent by weight, based on the overall weight of the composition, of a polyoxyalkylene glycol, and drawing the resulting filaments; (c) that obtained by melt-spinning a blended composition of 99.5 - 60 percent by weight of polyester and 0.5 - 40 percent by weight of a polyamide blend containing, based on the overall weight of the composition, 1 - 30 percent by weight of a polyoxyalkylene glycol, and drawing the resulting filaments; (d) that obtained by melt-spinning a blended composition of 60 - 99.5 percent by weight of polyester, 0.5 - 40 percent by weight of polyamide and 0.6 - 30 percent by weight of polyoxyalkylene glycol and drawing the resulting filaments; (e) that obtained by melt-spinning a blended composition of 60 - 99.5 percent by weight of polyester and 40 - 0.5 percent by weight of polyamide, drawing the resulting filaments, followed by heat treating and shrinking the filaments, and thereafter again drawing the filaments; (f) that obtained by melt-spinning a blended composition of 60 -99.5 percent by weight of polyester and 40 - 0.5 percent by weight of polyamide, drawing the resulting filaments, followed by shrinking the filaments 2 to 50 percent of their initial length by heating the filaments at a temperature within the range of 140*C. and the melting temperature of said polyester filaments and thereafter again drawing the filaments, and (g) that obtained by melt-spinning a blended composition of 60 -99.5 percent by weight of polyester and 40 - 0.5 percent by weight of polyamide, drawing the resulting filaments, followed by heat treating and shrinking the filaments, and thereafter again drawing said filaments at a rate of elongation ranging from 2 percent of their initial length to the point at which breakage of said polyester filaments takes place, at a temperature within the range of room temperature and 230*C.
 3. A method of dyeing a modified polyester textile fiber which comprises dyeing said fiber with an anionic dyestuff in the presence of tributyl phosphine or triphenyl phosphine. 